Quote:
Originally Posted by sambo
What generally causes this extreme cam lobe wear - uneven spring rates?
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It could be a spring on the light side of minimum full open spec.
Once the roller starts to skip, the flat spots start happening and it's goodbye roller wheel and cam lobe. I have seen more than one failure in an engine, but generally only one failure per engine.
For only one from sixteen to fail is extremely odd, I can't put it down to anything else.
Quote:
Originally Posted by Modena
the original spec lifters are shi-te apparently - there is an upgrade kit that goes in to replace them, for those that fail under warranty of course.....
the cam part itself is ok and although it is screwed by the dodgy lifters, the new replacement is not an upgraded part I believe, just a new one of the same design.
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I think it is a hardness issue combined with light valve springs.
The springs would be the lightest GM could use to allow the engine to rev to factory fuel cut, and not be too heavy for fuel economy loss.